This invention relates to liquid agitators and more particularly to means for suppressing vibrations in these agitators.
It is common practice in the chemical, food and beverage processing industries, among others, to mix materials in polymerizers, reactors, mixers and the like with agitators having blades extending from a rotary shaft located in the central portion of the vessel. One problem with these agitators is that relative motion between the liquid being agitated and the blades induces vibrations in the agitator. These vibrations can damage the glass linings frequently used on the agitators and/or the shaft seals and bearings that support the agitator. Furthermore, the vibrations may be transmitted to the vessel and to piping systems connected thereto, causing damage to these elements as well as to the agitator itself.
One conventional method of suppressing these vibrations is to mount the tip end of the agitator shaft in a bearing located at the bottom of the vessel, as described in Japanese Utility Model 10742/1960 and schematically illustrated in FIG. 1. However, complicated bearing structures are required in order to prevent entry of liquids inside the vessel which might corrode or abrade the bearing. Furthermore, discharge openings are frequently located in the bottom of the vessel at the same spot where it would be most desirable to mount such a bearing.
Attempts have also been made to suppress these vibrations by mounting a cylindrical stabilizer, as illustrated in FIG. 2, at the free tip end of the agitator shaft. However, stabilizers of this sort have not proved satisfactory.